Abstract: Hemocytes are the major immune cells of crustaceans. They remove invading pathogens by phagocytosis, encapsulation, nodulation and releasing of immune reactive molecules. Hematopoiesis is important for renewal and replenishment of circulating hemocytes and maintenance of a functional immune system. Compared with the hematopoiesis of vertebrates, which has been intensively studied, the knowledge of the invertebrate hematopoiesis is limited. In this review, we summarize the current knowledge of crustacean hemocyte lineages and their function, the structure and cell content of hematopoietic tissue, the differentiation procedure of hemocytes, and the regulation of hematopoiesis. We also introduce the in vitro methods developed for the study of crustacean hematopoiesis. Finally, we raise the questions needed for the future study.